On the Corona of the Sun. 



125 



The existence of a force, which, under suitable conditions, may 

 become one of repulsion at the sun's surface, is not hypothetical only, 

 for we have reasons to believe that such a force must really be present 

 there. Though we have no definite knowledge of the distribution of 

 electricity on the surface of the sun, we do know that chemical and 

 mechanical actions are taking place there which must be accompanied 

 by electrical disturbances. Ifc seems to me that these disturbances, 

 which must be of a high order of magnitude, bring about the magnetic 

 changes on the earth which are observed to take place in connexion 

 with solar phenomena.* 



The grandest displays of terrestrial electrical disturbance must be 

 altogether insignificant in comparison with the electrical changes 

 which must accompany the ceaseless and fearful activity of the 

 photosphere. ~Not to mention the frequent outbursts of heated gas 

 thousands of miles high, and over areas in which the earth could be 

 engulphed, there is the unceasing formation of the fiery photospheric 

 cloud-granules about as large as Great Britain. Surely it is not too 

 much to say that our terrestrial experience of lightning and of 



his discussions of Donati's comet, which were printed in this Journal some years 

 ago. Professor Winlock also informs me that he has held and published a very 

 similar opinion, and so I think have more than one of the European astronomers. 

 My own father, more than twenty years ago, was accustomed to teach from the same 

 chair of astronomy which I now occupy, an essentially similar doctrine. Thus the 

 idea had long been familiar to me, and, I presume, more or less so to astronomers 

 generally." 



It may be well to give a more direct reference to the papers of Professor W. A. 

 Norton. He says, speaking of comets (" Proc. Amer. Ass.," 1854, p. 166) : — " The 



tails of comets flowing away under a repulsive force from the sun." 



" [this repulsive force] to consist of the impulsive action of auroral matter flowing 

 from the sun." Again, speaking of the corona, he says : " The aigrettes of auroral 

 matter flowing off chiefly from the polar regions into space." In a subsequent 

 paper ("Proc. Amer. Ass.," 1859, p. 167) Professor Norton defines his idea of the 

 repulsive force as "a general force of cosmical repulsion exerted by all cosmical 

 masses." 



Mr. Proctor's views will be found in his work, "The Sun, the Euler of the 

 Planetary System," 3rd Ed., 1885, pp. 326—427. 



Eor M. Faye's views on a repulsive force, see " Annuaire pour l'An 1883," also 

 "Annuaire pour l'An 1885," and numerous papers in the "Comptes Eendus." 

 Reference should also be made to the conjectures on the existence of a repulsive 

 force thrown out by Sir John Herschel in his Cape Observations. 



* Professor Stokes and Professor Balfour Stewart have both speculated on the 

 connexion between solar disturbances and terrestrial magnetism, and have both 

 imagined that the operative solar change is thermic — not electrical, and that it is 

 through radiation that it affects the condition of the earth in such a manner as to 

 be manifested by magnetic disturbances, though the modes in which these philoso- 

 phers have conjectured that this takes place are wholly different. In a subsequent 

 note I have suggested that the operative solar change is electrical, and that the 

 action is probably one of statical induction. — August 20, 1885. 



